Such slides, used to adjust the longitudinal position of a seat, conventionally include a fixed section, attached to the floor of the vehicle, and a movable section, attached to the frame of the seat and sliding longitudinally in relation to the fixed section. Locking means, conventionally attached to the movable section, ensure the locking of the movable section on the fixed section, in the position chosen by the user, by mating with the notches of at least one row of notches made on the said fixed section.
The locking thus made must ensure reliable securing of the seat in relation to the vehicle, especially during impacts or accidents which may have a tendency to move the seat forwards or rearwards.
We already know of various slide systems consisting of a male section sliding in relation to a female section.
According to a first type of slide, the male section constitutes the fixed section, attached to the floor, and the female section is attached to the frame of the seat. Locking is then ensured by a lock attached to the female section in the longitudinal sliding direction and movable crosswise to this direction by means of unlocking control elements. The lock conventionally includes several teeth which engage with the notches of the male profile and are maintained in position by elastic recall means to ensure the locking. The unlocking control elements enable the teeth of the lock to be disengaged from the notches to enable the female section to slide and therefore the adjustment of the position of the seat.
In a second type of slide, the male section is attached to the frame of the seat and the female section is attached to the floor. The lock is then connected to the male section and its teeth mate with the notches of the female section.
French patent document FR-A-2 736 311 describes a slide of the latter type where the female section is generally U-shaped in section, has two flanges which extend towards the inside of the section by inner flange returns, and the male section is also generally U-shaped in section, the flanges of which are located between the inner flange returns of the female section and extend towards the outside by outer flange returns which are folded under the inner flange returns of the female section, and extend respectively between the latter and the flanges of the female section.
The outer flange returns of the male section constitute, with the flanges and inner flange returns of the female section, raceways for balls facilitating the relative sliding of the male and female sections. The locking means include a lock consisting of an elastically flexible strip, for example made of spring steel, placed on the inside of the slide and attached at one end to the male section. The other end of this strip includes, on each side, locking teeth which are guided, crosswise to the sliding direction, in the cutouts made in the angles formed by the flanges and the outer flange returns of the male section and which mate, in locking position, with the notches of the two rows of notches made respectively on the edges of the inner flange returns of the female section. Unlocking is ensured by an arm of a control bar, which penetrates into the slide and the end of which acts on the lock to disengage the teeth from the notches by deflecting the blade crosswise to the sliding direction, return to locking position being ensured by the elastic recall of the said strip when the bar is released. The locking ensured by this system is especially resistant to forces tending to make the male section slide, thanks especially to the fact that the rows of notches of the female section are located directly against the wall of the male section in which the teeth guide cutouts are made and, therefore, the loads mainly generate shear stresses on the teeth, excluding all other stresses on the lock itself or its attachment.
The principle of this locking system, consisting in transforming the relative movement forces of the two sections of a slide into shear stresses in the teeth of the lock, can be applied to other types of slides than those described in the above mentioned document, in particular to slides of the first type mentioned above.
However, during an accident, the lock may move to the unlocking position under the effect of an impact and the seat may then slide.
The aim of this invention is to solve this problem and, especially, to provide, in addition to the high locking resistance mentioned above, high reliability and an improvement in safety by preventing all unwanted unlocking.